Exchangeable lenses for cameras are fitted to the cameras by screwing the lens tubes which are cylindrical molded products of various kinds into the cameras. These lens tubes are produced from molding materials reinforced with glass fibers or the like. However, such a glass fiber-reinforced molded product has a disadvantage that glass fibers exposed on the product surface impair the smoothness and sliding property of the product. On the other hand, moving parts such as gears, cams, etc., for OA machines and apparatus have conventionally been manufactured by molding aromatic polycarbonate resin compositions containing a lubricating filler and/or a slip agent, such as a fluoroplastic, molybdenum disulfide, silicone oil, etc. However, such moving parts are defective in that, for example, a gear having tooth tops of 1.0 mm or less has poor fatigue resistance and, hence, has a short life.
It has been proposed to conduct molding at higher mold temperatures in order to prevent glass fibers from being exposed on the surface of the molded product. This technique, however, newly causes problems in that it is necessary to use a longer cooling time, resulting in an elongated molding cycle, and that mold-release properties are impaired. It has also been proposed to use reinforcements such as potassium titanate whiskers and asbestos, which are finer than glass fibers, from the standpoint that in producing a gear or other parts by molding a glass fiber-reinforced material, glass fibers tend not to be present in the end portions of the thin teeth of the molded gear, etc., so that the thin teeth have insufficient fatigue resistance. However, the above-proposed reinforcements decompose and deteriorate aromatic polycarbonate resins to rather impair the properties of the molded products.
Some of the present inventors previously succeeded to produce, on an industrial scale, zinc oxide whiskers, each comprising a core and four acicular-crystal arms extending from the core in different directions, the acicular-crystal arms each having a diameter as measured at the root thereof of from 0.7 to 14 .mu.m and a length as measured from the root to the end thereof of from 3 to 200 .mu.m, by a novel process as described in JP-A-62-334418 and JP-A-63-41330. (The term "JP-A" as used herein means an "unexamined published Japanese patent application".)